The proposed project represents a unique collaborative effort between a researcher who ordinarily conducts research on behavioral treatments in developmental disabilities, and the co-principal investigator who has an established record of operant laboratory research. The goal is to evaluate a behavioral treatment (response-independent reinforcement schedules) using animal models and standard operant laboratory procedures. Response-independent schedules have been used recently as treatment for severe behavior disorders such as self-injury and aggression. In general, response-independent schedules are effective because they break the contingency between a behavior and some reinforcing consequence. However, as with all behavioral treatments, response-independent schedules are not always effective. Some possible factors leading to treatment efficacy or inefficacy will be evaluated in these studies. Lever pressing in rats will be initially reinforced on a response-dependent schedule (i.e., responding will produce access to food reinforcers; this mimics "pretreatment" conditions). Next, response-independent schedules will be introduced (i.e., responding will have no effect on reinforcer delivery; this mimics "treatment"). The first specific aim is to evaluate the effects of response-independent schedules as a function of similarity or dissimilarity to baseline reinforcer rates. The second specific aim is to evaluate whether a single response-independent schedule (i.e., one treatment) is influenced by the response-dependent baseline that precedes it. The baselines and treatments will either be similar or dissimilar in the sense that reinforcers will be delivered variably or on a set schedule. In relation to both specific aims, it is hypothesized that treatments will be more effective when they are relatively distinct from baseline (either in terms of reinforcer rate or reinforcer presentation format). The long-term objective of these projects is to initiate an ongoing collaborative effort of basic and applied research related to behavioral treatments. In addition, the studies could lead directly to better application of response-independent treatment schedules.